A study in the May 1 issue of the journal Sleep is the first to examine sleep issues in a large sample of exceptionally old adults, including nearly 2,800 people who were 100 years of age and older.

Results show that about 65 percent of the sample reported that their sleep quality was good or very good, and the weighted average daily sleep time was about 7.5 hours including naps.

Health problems were associated with worse sleep quality, as participants with self-rated poor health were 46 percent less likely to report sleeping well. The odds of reporting good sleep quality also were lower in people who often felt anxious, had at least one chronic disease or struggled with everyday tasks.

"Age and health conditions are the two most important factors associated with self-reported sleep quality and duration," said principal investigator and lead author of the study Danan Gu, PhD, faculty of the Nohad A. Toulan School of Urban Studies and Planning at Portland State University in Oregon.

The study involved an analysis of data from the 2005 wave of the Chinese Longitudinal Healthy Longevity Survey. The sample was composed of 15,638 adults aged 65 and older, including 3,927 who were between 90 and 99 years of age, and 2,794 who were 100 years of age and older. Participants were spread across 22 provinces in mainland China.

According to the authors, China's population of more than 1.3 billion people includes the largest elderly population in the world, making the country a valuable resource for studying healthy longevity. The World Bank estimates that China has nearly 40.5 million people who are 75 years of age and older.

Source: American Academy of Sleep Medicine